Field
Exemplary embodiments relate to a low drop-out (LDO) regulator, and, more particularly, to an LDO regulator with improved power supply rejection ratio (PSRR) and a display device including the same.
Discussion
Voltage regulators may be used to provide stable power to electronic devices, such as display devices, or components thereof. The voltage regulators may be classified into switching regulators and linear regulators.
A direct current (DC)-to-DC converter is a type of switching regulator that may, in comparison to linear regulators, exhibit relatively high conversion efficiency, but may produce noise in output voltages. An LDO regulator is a type of linear regulator that may have relatively lower conversion efficiency, but may have relatively high response speed. An output voltage from an LDO regulator may be less than an input voltage supplied thereto, and, as such, may incur a power loss. It is noted, however, that the LDO regulator may provide a stable power output. Further, the output voltage of the LDO regulator may include less noise than the noise in the output voltage of a DC-to-DC converter. Accordingly, an LDO regulator may replace or supplement a DC-to-DC converter to supply power in noise-sensitive electronic devices or high performance electronic devices.
A power supply rejection ratio (PSRR) is a ratio between noise in an input voltage supplied to a power supply and noise in an output voltage. The PSRR may indicate a level of stability in supplying voltage by a voltage regulator in a determined frequency range, through which noise in the input voltage may be reduced. In a voltage regulator, noise in an input voltage may prevent it from maintaining a stable output voltage. Since effectively blocking noise from the input voltage supplied to a voltage regulator in a high frequency range (which may be higher than a gain crossover frequency in a closed loop of the linear regulator by hundreds of KHz or MHz) may be difficult, it is concomitantly difficult to maintain a stable output voltage in the high frequency range.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the inventive concept, and, therefore, it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.